1. Field of the Invention
The present invention generally relates to a production control system applicable to a production line including processing equipment such as manufacturing, testing, and correcting apparatuses and physical distribution equipment and, more particularly, to a production control system effectively achieving multikind and small-quantity production.
With the recent reduction in size, lightening in weight, and diversification of functioning of products in the field of electronic equipment, printed circuit board units constituting such equipment are increasing their packaging density. As a result, these component parts are increasing in number and becoming more and more miniaturized and complicated. Consequently, it has become difficult to mount such component parts by manual operation and, hence, many factories have come to introduce various automatic parts mounting machines. Because of increase in labor costs, effective and unmanned running of such expensive machines to a highest possible degree are desired by those factories. On account of diversification of customers'needs and decrease in life cycle of products, factories are compelled to do multikind and small-quantity production and to deliver their products in short delivery times. Also for this reason, there are great desires for attainment of unmanned and high-efficiency operations of production lines.
2. Description of the Related Art
Various attempts have so far been made to practice unmanned and high-efficiency operation of an individual apparatus disposed in a production line, for processing a single kind of product. However, a system achieving synthesized unmanned and high-efficiency operation of a system for an entire production line capable of manufacturing a variety of products is not yet developed to the stage where it is put to practical use.
As a method for achieving synthesized unmanned and high-efficiency operation of a system including an entire production line, there is one in which physical distribution and dealing (assembling, testing, correction, etc.) with objects to be processed are executed in accordance with prescribed programs. However, in such system with sequential control, as it is called, applied to an entire line, it has been difficult to quickly respond to a change in the kind of product and, hence, it has been difficult to achieve effective multikind and small-quantity production.